RRC Running super rich

[Mister_white_keys]

Hi Everybody,

I've been playing with my old 2 door and have run into a bit of a problem with it running waaaaaay too rich. First some details on the car.

It's a 1975 2 door RRC that I've recently put a P76 4.4v8 into along with a replacement LT95 4 speed gearbox. The 4.4 came with twin Solex CD175's on a manifold but when I did the engine change I stuck with the Holley 350 I had been running just to eliminate a variable in getting the second hand motor up and running again.

Fast forward to now, and I've decided to put the twins back on since everyone tells me they're better for off roading and I've got a soft spot for twin carbs as I dearly love the twin SU's I've got on my mini.

Figuring that since these carbs came off the motor that's in the car, I gave the CD175's a good check over and thought I'd give them a try on the car. The carbs look to be in good condition, all nice and clean and the diaphragms are intact as well as still being soft and pliable and not hard or cracked.

I've made up a tool to adjust the needle height as these are the later types that don't have an adjustable jet and even with the needles on their leanest setting, the car is still running super rich. I can get it to idle roughly but it is belching out smoke and the 2 colourtune plugs I've got in it show it on the super rich side of the spectrum.

I'm after some suggestions of what to check in regards to trying to get these things working. I did notice that the choke lever doesn't move the jets down as it would in an SU (or many other carbs I've seen), do these have some sort of auto choke or does the choke raise the dashpots instead?

Any help or suggestions would be greatly appreciated. I don't want to go back to the Holley as it means draining the coolant out again and I'd prefer to get the look of the twins back in the engine bay.

Is there a preferred needle and jet size that people have used for the 4.4's? If so does anyone know the measurements so I can compare what is in there?

Thanks in advance,
Steve

[PLR]

G`day ,

the choke will most likely be the disc type , it should only be on the left hand carb .

It meters fuel rather than air flow like most things , the disc has 3 or 4 holes of different sizes and as the disc rotates when the cable is pulled it opens the holes .

If it`s set up like a normal 3.5 , each carb feeds 4 cylinders so if you pull the plugs and find four dark and four not so much , it may be that only one carb is playing up .

i`m pressuming you checked the float levels when you cleaned them , and put the pistons the right way .

Ours has CDs and LPG as well , it was running very rich at one stage on petrol but i can remember what the problem was , i must have fixed it because it doesn`t blow black any more , i do remember it was nothing to do with jets or the choke .

[Mister_white_keys]

Thanks Peter,

Admittedly, I checked the float bowls for dirt etc. but didn't check the float levels so that will be the next port of call. Interesting about the disc choke, haven't seen one like that before.

In terms of the pistons being around the right way, I've put them back in so the rectangular notch on the rubber diaphragm lines up with the recess in the housing, I'm assuming that is the right way around but if there's another way to easily tell I'll check that too.

In the fiddling I've done, it seems that the passenger side carb is running much richer than the drivers side (based both on the colourtune and lifting the piston slightly while running) but both have the same needle settings and I've balanced them as much as I can with a bit of hose to my ear.

More checks to be done!

Cheers,
Steve

[PLR]

Thanks Peter,

Admittedly, I checked the float bowls for dirt etc. but didn't check the float levels so that will be the next port of call. Interesting about the disc choke, haven't seen one like that before.

In terms of the pistons being around the right way, I've put them back in so the rectangular notch on the rubber diaphragm lines up with the recess in the housing, I'm assuming that is the right way around but if there's another way to easily tell I'll check that too.

In the fiddling I've done, it seems that the passenger side carb is running much richer than the drivers side (based both on the colourtune and lifting the piston slightly while running) but both have the same needle settings and I've balanced them as much as I can with a bit of hose to my ear.

More checks to be done!

Cheers,
Steve

G`day Steve ,

as long as the same thing was done with piston and diaphragm they must be the right way .


You may know but the float level is 16mm to 17mm from the gasket surface to the float top (upside down ) .

Clockwise is rich .

The start point for the needle is usually , needle shoulder flush with piston face .

If the CD 175 carbs are from a 3.5 RR and have the original needles , should be one of these .

B2AS

B1DW

B1EJ

B1FH

They are all top adjust type .

I guess you had a look at the tapper of the needles for obvious wear .

Back in the early 70s a mate had what we called a Mini panel van , maybe it wasn`t , great little car though , nothing to do a 130km round trip to go to the drive in .

Cheers

[Mister_white_keys]

Thanks for the extra info, that'll be most helpful. I'm hoping to get out into the shed and have a play with them in the next day or so.

I've got a 1964 mini van and love it dearly, it's travelled up and down the east coast of Australia as well as competed in various forms of club motorsport including motorkhana, autocross and hillclimb. I bought it when I was 17 and rebuilt the whole car over a few years, it's a magical little car that always puts a smile on my face :)

[Mister_white_keys]

Alright, update time.

I've taken the passenger side carb off and checked the float level which is bang on at about 17mm. While having a look though I think I may have found the problem, upon closer inspection of the needles (which are B1FH) I've found some wear on one side of both of them. The photo probably doesn't show much but the upward facing side has wear on it to flatten the round off slightly.

https://www.aulro.com/afvb/images/imported/2016/08/491.jpg (http://s241.photobucket.com/user/mister_white_keys/media/DSC_1553.jpg.html)

It seems to be a significant amount of wear, I'm assuming from either lots of use or some misalignment of jets and needles.

So, the new questions is whether to replace just the needles, or both the needles and jets and also does anyone know a good set of needles and jets for the 4.4l motor?

[PLR]

There may be more info on a 4.6 with carbs and probably the UK would be where to look .

I haven`t looked for a while but there used to be places in the UK that reconditioned them and they may have what you want .

Although unless you intend to tow heavy stuff alot or run full throttle most of the time the std ones may work well enough , the reason i say this is because our 4.0ltr has held full throttle for 2 , 3 minutes or better towing a tandem with a RR on it up hills in mid summer and running lean hasn`t been a problem with it .

Though yours is a bigger capacity .

The B1FH needle belong to carbs that came from what is know as a high compression engine 9.35:1 , if the butterflies have poppet valves fitted it could be telling they are around 1985 and the last of this type we got here .

[Mister_white_keys]

Excellent, I'll have a look around thanks.

This car is mainly a camping truck with the occasional bit of off roading so not chasing super power or anything. I'll have a look around but might end up with the same needles and see how they go. I can always run it slightly richer if need be but the 4.4 runs at much lower revs than the 3.5 so might be alright.

Yes, the butterflies have the poppet valves in them (I assume to help with a smooth idle?) so it does look like these are off a late model. For memory I was told the 4.4 and these carbies were fitted into an 85 RRC so that all fits as well.

My only other concern is all the various vacuum ports on the carbs, I assume they were originally for the anti pollution gear such as charcoal canister etc. so have just blocked them all off. The only open airways are for the main intakes, dizzy advance and rocker cover vents. In addition to the manifold vacuum ports for the centre diff and the brake booster.

Unless some of these ports are for carb balancing perhaps?

[PLR]

Not that i know of just the ones that go over the main orifices .

The adapters between carb and the aircleaner pipe is where the canister pipes go .

The poppets are an emission thing , they let some air/fuel through on over run which is supposed to produce less hydrocarbon or what ever it is .

The early ones didn`t have them , just a flat disc they are interchangeable .

Some have removed them and soldered the cover of the valve back on because it would slightly improve airflow .

[Mister_white_keys]

Ok, finally had some time to play with the old girl and it looks like I'm on the right track.

I've put rebuild kits through both the carbies including new diaphragms, main jets and needle & seats.

I've also taken the advice of the blokes at Ritters and put some B1AQ needles as this is apparently what they used to run in the 4.4 conversions as well as the 4.6 and 4.2 strokers.

It's taken a bit of fiddling but it looks like I've got a good idle mixture now and it definitely drives a whole heap better than it ever did with the Holley on it.

Another quick question is about the ignition timing. I was running it at TDC just as a starting point and with the road testing I've got it running better with 3 degrees advance. It still doesn't seem quite right through the rev range so was thinking of taking it to 5 degrees. Just wondering what the general consensus is in regards to the ignition timing. It's running the standard 3.5l dizzy from a 75 model in the 4.4.

Cheers for all the help so far!

[Davo]

Many Rover V8s are happy at 12 degrees BTDC. You can adjust yours that far as long as it doesn't ping under load.

Do some research into what hose goes where so that you don't block off something important, as these engines do need to be set up specifically to run well.

[bee utey]

The high comp 4.4 car engine should run well at 5 degrees, a low comp Terrier engine could probably handle a little more. It also depends on what octane fuel you are running.

[Mister_white_keys]

Thanks guys,

It's a p76 motor and I usually run it on standard 91 octane. I'll try it at 5 degrees and see how it goes, otherwise I'll slowly increase the advance until it pings and then bring it back a smidge.

Cheers,
Steve